1. Technical Field
The present disclosure generally relates to seismic prospecting and in particular to methods and apparatus for acquiring and processing geophysical information.
2. Background Information
In the oil and gas exploration industry, geophysical tools and techniques are commonly employed in order to identify a subterranean structure having potential hydrocarbon deposits. Many of these techniques and tools utilize energy in the form of seismic waves to determine subterranean properties, and techniques utilizing seismic waves are often commonly referred to as seismic exploration. Seismic exploration is used in many cases to generate images of subsurface structures by recording energy in the form of vibrations after the energy has been imparted into the earth and has reflected or refracted from geologic formations.
In seismic exploration, seismic waves travel through the ground and reflect off rocks in the subsurface. Boundaries between different rocks often reflect seismic waves, and information relating to these waves is collected and processed to generate a representation or “pictures” of the subsurface. Any number of exploration systems may be used to gather the desired information for processing. Dynamite explosions, vibrator trucks, air guns or the like may be used to create the seismic waves, and sensors such as velocity geophones, accelerometers and/or hydrophones may be laid out in lines, or towed in the case of hydrophones, for measuring the amplitude of waves due to the seismic source, reflected off rock boundaries, and then returning to the deployed sensors.
A two-dimensional image, which is called a seismic line, is essentially a cross-sectional view of the earth oriented parallel to a line of sensors such as geophones. The information may also be collected as an intersecting grid of seismic lines referred to as a 3-D seismic volume.
Seismic prospecting today generally results in an extremely vast amount of information to be processed in order to obtain a subsurface image. Information in the form of signals representing acquired seismic information often includes additional noise signals that may often require processing the information to obtain the more desirable seismic information. Removal of the noise portion of the signal simplifies processing of the desirable seismic information.